Abstract: Objective To investigate the association between the dietary diversity score (DDS) and cardiometabolic multimorbidity (CMM) among middle-aged and older populations in China, utilizing data from the China Health and Retirement Longitudinal Study (CHARLS). Methods A cross-sectional study design was employed using data from the 2020 wave of CHARLS. A total of 8 174 middle-aged and older adults were included and subsequently categorized into a CMM group (n=3 268) and a non-CMM group (n=4 906) based on the presence of cardiometabolic multimorbidity. The association between DDS and CMM was evaluated using multivariable logistic regression, restricted cubic splines (RCS), and urban-rural stratified regression analyses. Results The mean DDS among the 8 174 participants was 8.50 ± 4.56. The cohort was stratified by DDS into low (2 297 individuals, 28.10%), moderate (4 165 individuals, 50.95%), and high (1 712 individuals, 20.94%) dietary diversity categories. Multivariable logistic regression analysis demonstrated that age, sex, educational attainment, lifestyle patterns, physical activity levels, family history of cardiovascular disease, nocturnal sleep duration, and DDS were significantly associated with the prevalence of CMM (all P<0.01). RCS analysis revealed a nonlinear dose-response relationship between DDS and the risk of CMM. Urban-rural stratified analyses indicated that a low DDS was associated with an elevated risk of CMM among rural populations (OR=1.144, 95% CI: 1.014-1.290, P=0.029). Conversely, this association was attenuated in urban populations, where only a high DDS exhibited a marginal protective effect (OR=1.151, 95% CI: 1.003-1.321, P=0.046). Conclusion The dietary diversity score is significantly and nonlinearly associated with cardiometabolic multimorbidity among middle-aged and older adults in China. Furthermore, substantial urban-rural heterogeneity exists in this association, with the risk of CMM being particularly pronounced among rural populations exhibiting low dietary diversity.

Key words: Cardiometabolic multimorbidity, Middle aged and elderly, Dietary diversity, China Health and Retirement Longitudinal Study, Association, Urban-rural disparities